You should be returning the boolean values true or false, not the strings "true" or "false".

Edit: Note that in production code, you shouldn’t be using the ternary operator at all for this type of thing; if you need to return a boolean based on a condition, you should simply write return <condition> (for example: return a === b). This won’t pass the tests, because it doesn’t use the conditional operator, but it is functionally equivalent.